Oil well control system



April 24, 1951 G. A. SMITH 2,550,093

OIL WELL CONTROL SYSTEM Filed March 15, 1949 2 Sheets-Sheet 1 April 24,1951 I G. A. SMITH 2,550,093

OIL WELL CONTROL SYSTEM Filed March 15, 1949 I 2 Sheets-Sheet 2 PatentedApr. 24, 1951 UNITED STATES PATENT OFFICE OIL WELL CONTROL SYSTEMGrafton A. Smith, Tulsa, Okla., assignor to Shell Development Company,San Francisco, Calif a corporation of Delaware Application March 15,1949, Serial No. 81,573

Glaims.

This invention pertains to a system for controlling the operation of oilwell pumps, and relates more particularly to an automatic system for thecontrol of electrically driven pumps in wells producing small quantitiesof fluid.

In many wells, especially during the later stages of their exploitation;the quantity of fluid entering the borehole fromthe formation is oftenless than that which can be readily handled by the pumping equipment,that is, the volumetric capacity of the pumping equipment installed atthe well is such that a sustained operation'thereof results in pumpingthe well oil or dry; Under these conditions, it is usual to produce suchwells by intermittent pumping, so that the fluid is permitted toaccumulate in the borehole during pump shut-down periods, and isexhausted from the well during alternate pump operation periods.

Such intermittent operation of the well pumping equipment may becontrolled either manually,

off at a time when considerable oil remains in the borehole, thuslowering the efficiency of the pumping operations, or the pumping periodmay be cut ofi only long after the borehole has been pumpedsubstantially dry, thus increasing the wear on the pumping equipment andwasting power.

It is, therefore, an object of this invention to provide a well-pumpingcontrol systemwherein the duration of the pumping period isautomatically adjusted to the amount of fluid available for umping froma well during said pumping period.

It is also an object of this invention to provide a well -pumpingcontrol system wherein the operation or" the pump is automaticallystopped when the fluid in the borehole is depleted;

Another object of this invention is to provide a system wherein eachpumping period is started by an automatic time-responsive device, andisterminated by an automatic device responsive to well conditions.

These and other objects of this invention will be understood from thefollowing description taken with reference to the attached drawing,

wherein The main disadvantage of Figure 1 is a diagrammatic sketchillustrating the component parts of the present system;

Figure 2 is a view, partly in cross-section, of

the flow-responsive device and pump shut-off ele-' of a sucker rodstring H, the well fluid lifted to 1 the surface being directed tostorage through a pipe I2. The sucker rod string II is reciprocated inthe well by the oscillating motion of a walking beam it, which isdriven, through a pitman l4, crank l5 and speed reducing mechanism It,by a prime-mover ll such as an electric motor receiving its powerthrough leads I8 and I9. It is understood that any suitable type ofmotor or engine may be used as the prime mover I1, such,

for example as a gasoline engine having its energizing ignition currentsupplied through leads l8 and I9. f

The control circuit of the pump motor 11 comprises three controlswitches 20, 2i and 22 that are connected in parallel between the motorI! and a power source 23. Switch 20'is a normally open hand-operatedswitch which, when closed, places the pump I! in continuous operation.Control switch 2| is normally open being adapted tobe closed by atime-responsive device such :as'

an electric or spring driven clock mechanism 24 of any desired type. Forsimplicity, this mechanism' is shown in Figure 1 as comprising arotating wheel or disc 25 provided with a segment adapted to close theswitch 21 by contact therewith. It will be seen that the time at'whichthe switch 2| isclosed and opened can be accurately pre-set orcontrolled by suitably adjusting the speed of rotation of the-disc 25and/or the size of the segment 26.

Control switch 22 is normally closed all the time that fluid is beingpumped from the well borehole and through the delivery line 2|.Preferably, switch 22 is small in size, such as a microswitch, or asealed-mercury type switch. The switch 22 is mounted on, and adapted tobe actuated by, a flow-responsive controller device 2! which is in turnconnected through suitable linkage means to the gate or flapper o'facheck valve 29-inline l2.

As shown inFigure-Z, the flow-responsive conbolts'33 to flanges 34' and35 in the pipe line I2. Thecheck valve 29 is of the globe type having a3 vertical-lift gate or disc 35 with a beveled edge 3? adapted to beseated in a beveled edge horizontal valve seat 38 surrounding the valveopening 39. Preferably, a plate 41) of suitable thickness is fixedlysecured to or integrally formed on the bottom of the disc 36, said plateMl having a diameter substantially equal to that of the valve opening 39and adapted to close said opening 39. A plurality ofdownwardly-extending guide bars 4! may be secured to the lower side ofthe plate 45 and disc 36 for guiding said disc into its proper seatingposition on closing, and for maintaining the disc 38 in a fixed positionwith regard to the valve opening 39 when the valve is open.

A valve bonnet 42 having a lower flange 43 is secured by bolts 44 to aflange 55 of the valve body 30; A valve stem 46 is secured in either afixed, or. hinged manner to the top of the valve disc 36, said stem 46extending upwardly into the bonnet 42. The disc 36 of the check valve isnormally maintained in a closed position by a compression spring Allthat surrounds the valve stem 45 and bears against the top of the disc36. Compression of the spring mil may be adjusted, without dismantlingthe valve, by an adjustment screw 48 through the top 9 of the bonnet 52,said screw being adapted-to be fixedly held in place by a lock nut 50.Interposed between said compression spring 47 and screw 48 is a suitableyoke means comprising either a slotted tubular member, ,or a ring and aplate 52 maintained in fixed space'relationship to each other by atleast two, and preferably four, spacing bars 63, said yoke meansbeingpositioned in said valve bonnet s2 so that said spring 4'! andscrew 48 bear against the ring 5| anddisc 35, respectively.

'Ahole, 53, drilledthrough the side wall of the bonnet 42 and fittedwith abushing or bearing 54,

serves as-bearing means for a horizontalshaft 55 which extends into saidbonnet above and vto one side of 55, as seen from Figure 5. A recess 56-may be drilled in the inner wall of the bonnet 42 diametricallyopposite hole 53, said recess 55 serving as bearing means for the end ofthe shaft 55 positioned within the bonnet 32. The shaft 55 and thetapered and drilled upper end 51 of the valve stem are operativelyconnected together by a fiat link member 58 having a hole 59 '(Figure 5)through one end, whereby said shaft may pass through said hole 59. Theother end of the link 58 is slotted and drilled to fit around thetapered and drilled end 57 of the valve stem 55, the drilled ends ofsaid link 58 and said stem 45 being secured together in hingedrelationship by a pin 51! as shown in Figure 2. The link 58 is locked ina predetermined fixed position on the shaft 55,and between the spacingbars 53 of the yoke means, by a set screw 6|. The shaft 55 is suitablypacked in a fiuidtight manner around its bearing 54, said packing beingheld in'place by a packing nut 52 or any other suitable means.

Supporting means for related control equipment may be positionedadjacent the valve 29. In this embodiment, a platform '64 is shown inFigure 2 as being bolted to the flange 43 of the bonnet 42 beneath theextending shaft 55. Carried on said platform 64 are motor means, such asa clock mechanism, spring motor or small electric motor 55 having itsshaft 65 coupled, if desired, to the high speed shaft of suitable speedreducing means 61. Fixedly secured to the lowspeed shaft 68 of the speedreducer 61, by a set screw 59, is a ratchet wheel 75 which may beslowly-rotated at any predetermined .speed, say, one revolution perhour. Freely mounted for swinging on said shaft 68 adjacent the ratchetwheel H3 is an actuator or cam H formed with a small lever arm l2(Figure 3). Due to its shape and loose eccentric mounting on the shaft68, the cam H has a tendency to swing downward so that its longer andheavier end depends below said shaft. However, as will be explainedbelow, the cam H is normally maintained in a substantially horizontalposition by a pawl 13 (Figure 3) carried by said cam and actuated by aspring F4 to engage the teeth of the ratchet wheel 10. Thus, the ratchetwheel 10 and pawl 73 form overriding clutch means or adjustable couplingmeans between the drive shaft 68 and the actuator H. vents anyhorizontal movement of the cam H on said shaft 6%.

Affixed to the end of shaft 55 at a predetermined angle, by a set screw75, is a rocker arm 11 having an extending pin 18 secured to one end.Preferably, the low-speed shaft 68 of the speed reducer ismountedcoaxially with shaft 55 extending from the bonnet 42 of thevalve,whereby the rocker arm ll may be positionedso that its pin 18 extendsbeneath the cam H to establish contact therewith, as shown .in Figure 2.

Thus, any upward motion of the rocker arm 1T and pin i8 is transferredto the cam H.

The pump cut-off switch 22 is shown in Figures 2 and 3 as consisting of,a switch housing 19, a

through leadsfiz and 83. 'It is realized that any other suitable type ofswitch may be used and mounted with regard to the above describedequipment so that it will be opened by'a predetermined movement of thecam H. Thus, as

shown in Figure 4 a switch 84 of the mercury- I sealed type having leads85 andBB secured there to may be mounted on the arm??? of a cam88whereby-any movement of said cam 88 beyond a predetermined point willtilt theswitch 88 so that the mercury contained therein flows to one endof the switch housing thus opening said switch. I

The present pumping system may be put into operation by closing thehand-operated switch 2i! (Figure 1) to start the motor H which causesthe pump in the well It to be reciprocated. The l 1 fluid delivered "bythe pump surges or flows through the delivery line I2 with every strokeof the pump. Each surge of fluid through the line,

in the direction indicated by the arrow in Figure 2, causes the disc 35of the check valve to be raised vertically in the valve opening 39.Since there is a plate 40 secured to the bottom of the disc 36, thisplate 45 acts as a piston and nofluid starts to flow through the openingvalve until the gate has been raiseda distance equal to the of thepresent device.

As the disc 36 is raised against the compression .7 of the spring 41,the link member 58 is moved upwardrcausing the horizontal shaft 55 torotate,

for example, in a clockwise direction, when viewing the valve housingfrom the side of the motor 55. Th rocker arm ll, being fixedly attachedi to shaft 55 is also moved in a clockwise direction, ,.;that is, thearm H is moved upwardly so fth'at its pin TBcontacts the cam H andraises it so that A nut T5 at the end of shaft 68 pre-' This serves tocomits lever arm 12 is out of contact with the switch spring 8| thusallowing spring-loaded switch 22 to automatically close.

With the switch 22 closed the hand-operated switch 20 may be opened andthe motor [1 will continue to operate the pump as long as lever 12 doesnot contact and open switch 22, the operation being as follows: The camH is mounted loosely on shaft 68 and its center of gravity is disposedso that it tends to swing counter-clockwise on said shaft. However, thespring-loaded pawl 13 engages the cam H with the ratchet wheel 10, sothat the cam can move counterclockwise only together with said wheel,which is adjusted to rotate continuously at some suitable low speed,such as one revolution per hour. As the slow rotation of the wheel 10tends to bring the lever 12 of the cam TI into contact with switch 22 toopen said switch, this tendency is ,counteracted by the action of thepump, which forces a surge of fluid through the check valve 29, raisingstem 45 and actuating rocker arm 11 and pin 5'3 to rotate the cam llclockwise about its shaft whereby the pawl 13 is caused to disengage onetooth on the ratchet wheel and to engage another tooth further up. Thecam is thu maintained in a substantially horizontal or any other desiredpredetermined position by two opposing actions: the continuous slowrotation of the ratchet wheel in one direction, and the intermittentrotation in the reverse direction due to the lifting effect applied byrocker arm 11 and pin 18 every time that the valve 29 operates. However,when the well is dry, and fluid is no longer being pumped through thecheck valve 29, the valve disc 36 remains closed, and the link 58 androcker arm 11 no longer operate to counteract the steady rotation ofwheel Ill. With the rocker arm Ti and pin 18 at their lowermostposition, the cam I! slowly rotates with the ratchet wheel 19 in acounter-clockwise direction until the lever arm 12 of the cam H contactsthe spring 8| on the switch 22 and causes it to open shutting off thepump motor I1. I

Instead of being started manually by means of switch 20 the pump motormay be automatically started again, after a predetermined time interval,by the rotating segment 26 of the timeresponsive device which closes theswitch 2| and holds it close for the length of time that it takes forsaid segment 26 to rotate past the switch, say, 10 minutes, whereafterthe system is maintained in further operation by the switch 22 in themanner described above.

I claim as my invention:

1. A control system for a well installation comprising a reciprocatingwell pump, a prime mover for said pump, an energizing electric circuitfor said prime mover, and conduit means for the fluid delivered by saidpump, said control system comprising a normally closed switch in saidelectric circuit, adjustable actuator means for opening said switch uponmovement to a predetermined position, motor means for continuouslymoving said actuator means toward said position, check valve means insaid conduit means, and transmission means between said check valvemeans and said actuator means responsive to the periodic opening at eachpump stroke of said check valve means by the pump fluid for periodicallymoving said actuator means in a direction opposite to that of the motionof said motor means, whereby said actuator means are prevented fromopening said switch during the delivery of the pump fluid to saidconduit means.

2. A control system for a well installation comprising a reciprocatingwell pump, a prime mover for said pump, an energizing electric circuitfor said prime mover, and. a conduit for the fluid delivered by saidpump, said control system comprising a normally closed switch in saidelectric circuit, adjustable actuator means for opening said switch uponmovement to a predetermined position, slow-speed motor means forcontinuously moving said actuator means toward said position, a, checkvalve in said conduit, a vertical-lift disc in said check valve, a valvestem secured to the top of said disc, and linkage means between saidvalve stem and said actuator means responsive to the periodic opening ofsaid check valve by the pump fluid for periodically moving said actuatormeans in a direction opposite to that of the motion of. said motormeans, whereby said actuator means are prevented from opening saidswitch during the delivery of the pump fluid to said conduit means.

3. A control system for a well installation comprising a reciprocatingwell pump, a prime mover for said pump, an energizing electric circuitfor said prime mover, and a conduit for the fluid delivered by saidpump, said control system comprising a switch in said electric circuit,said switch being in a closed position while a fluid is being pumpedthrough said conduit, actuator means for opening said switch uponmovement to a predetermined position, slow-speed motor means, overridingclutch means coupling said motor means to said actuator means forcontinuously moving said actuator means toward said position, a checkvalve in said conduit, a verticallift disc in said check valve andtransmission means between said disc and said actuator means responsiveto the periodic opening of said check valve means by the pump fluid forperiodically moving said actuator means in a direction opposite to thatof the motion of said motor means, whereby said'actuator means areprevented from opening said switch during the delivery of the pump fluidto said conduit means.

4. A control system for a well installation comprising a reciprocatingwell pump, a prime mover for said pump, an energizing electric circuitfor said prime mover, and conduit means for the fluid delivered by saidpump, said control system comprising a normally closed switch in saidelectric circuit, a check valve in said conduit means, a vertical-liftdisc in said valve, a valve stem secured to the top of said disc andmovable therewith, a first shaft extending into said valve above saidvalve stem, linkage means connecting said valve stem and said shaftwhereby a vertical motion of the valve stem is translated into anintermittent rotation of said shaft, motor means mounted adjacent saidvalve, a second shaft continuously rotated by said motor means, aratchet wheel fixedly mounted on said second shaft, an actuator freelymounted on said second shaft, said actuator being adapted to open theswitch in the electric circuit upon movement to a predeterminedposition, a spring-loaded pawl mounted on said actuator for engagingsaid ratchet wheel whereby said actuator is continuously moved towardsaid position by said ratchet wheel and lever means mounted on saidfirst shaft, said lever means being responsive to the periodic openingof said check valve by the pump fluid for periodically moving saidactuator in a direction opposite to that of said ratchet wheel, wherebysaid actuator is prevented from opening said switch during the deliveryof thepump fluid to said conduit means.

5. A control system for a Well installation comprising a reciprocatingWell pump, a primer mover for said pump, an energizing electric circuitfor said prime moveryand conduit means for the fluid delivered by saidpump, said control system comprising first and second switches connectedin parallel in said electric circuit, said first switch being normallyclosed, said second switch being normally open, adjustable actuatormeans for opening said first switch upon movement to a predeterminedposition, motor means for continuously moving said actuator means towardsaid position, check valve means in said conduit, transmission meansbetween said check valve means and said actuator means responsive to theperiodic opening of said check valve means by the pump fluid forperiodically moving said 8 V actuator means in a direction opposite tothat of the motion of said motor means, whereby said actuator means areprevented from opening said switch during the delivery of the pump fluidto said conduit means, and time responsive control means for closingsaid second switch at predetermined time intervals.

GRAFTON A. SMITH.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

